1. Field of the Invention
The present invention relates to a technique for recording dots on the surface of a recording medium with the aid of a dot-recording head, and more particularly to a technique for printing images up to the edges of printing paper without soiling the platen.
2. Description of the Related Art
Printers in which ink is ejected from the nozzles of a print head have recently become popular as computer output devices. FIG. 19 is a side view depicting the periphery of a print head for a conventional printer. Printing paper P is supported on a platen 26o while facing the head 28o. The printing paper P is fed in the direction of arrow A by the upstream paper feed rollers 25p and 25q disposed upstream of the platen 26o and by the downstream paper peed rollers 25r and 25s disposed downstream of the platen 26o. Dots are recorded and images printed on the printing paper P when ink is ejected from the head.
When an attempt is made to print images up to the edges of printing paper with the aid of such a printer, it is necessary to arrange the printing paper such that the edges of the printing paper are disposed underneath the print head (that is, on the platen) and to cause ink droplets to be ejected from the print head. With such printing, however, the ink droplets sometimes miss the edges of the printing paper (for which the droplets have been originally intended) and end up depositing on the platen due to errors developing during the feeding of the printing paper, a shift in the impact location of the ink droplets, or the like. In such cases, the ink deposited on the platen soils the printing paper transported over the platen in the next step.
It is an object of the present invention, which was perfected in order to overcome the above-described shortcomings of the prior art, to provide a technique that allows images to be printed up to the edges of printing paper while preventing ink droplets from depositing on the platen.
Perfected in order to at least partially overcome the above-described shortcomings, the present invention envisages performing specific procedures with a dot-recording device for recording ink dots on a surface of a print medium with the aid of a dot-recording head provided with a group of dot-forming elements composed of a plurality of dot-forming elements for ejecting ink droplets. The dot-recording device comprises a main scanning unit, a head driver, a platen, a sub-scanning unit and a controller. The main scanning unit is configured to drive the dot-recording head and/or the print medium to perform main scanning. The head driver is configured to drive at least some of the dot-forming elements to form dots during the main scanning. The platen is configured to extend in a main scanning direction and to be disposed opposite the dot-forming elements at least along part of a main scan path. The platen is configured to support the print medium at a position opposite the dot-recording head. The sub-scanning unit is configured to move the print medium to perform sub-scanning across the main scanning direction in between the main scan paths. The controller configured to control the dot-recording device.
The platen comprises a first support member, a first slot, a second support member and a second slot. The first support member is configured to support the print medium. The first support member extends in the main scanning direction. The width of the first support member in a sub-scanning direction corresponds to a first sub-scanning range on a surface of the dot-recording head including a preselected first sub-group of dot-forming elements. The first slot extends in the main scanning direction. The width of the first slot in the sub-scanning direction corresponds to a second sub-scanning range on the surface of the dot-recording head including a preselected second sub-group of dot-forming elements. The second sub-group of dot-forming elements is disposed in the sub-scanning direction downstream from the first sub-group of dot-forming elements. The second support member is configured to support the print medium. The second support member extends in the main scanning direction. The width of the second support member in the sub-scanning direction corresponds to a third sub-scanning range on the surface of the dot-recording head including a preselected third sub-group of dot-forming elements. The third sub-group of dot-forming elements is disposed in the sub-scanning direction downstream from the second sub-group of dot-forming elements. The second slot extends in the main scanning direction. The width of the second slot in the sub-scanning direction corresponds to a fourth sub-scanning range on the surface of the dot-recording head including a preselected fourth sub-group of dot-forming elements. The fourth sub-group is disposed in the sub-scanning direction downstream from the third sub-group of dot-forming elements.
With this dot-recording device, printing is accomplished in the following manner. Here, the surface of the print medium is divided, in order from the front edge, into a front-edge portion containing the front edge, a front-edge transitional portion, an intermediate portion, a rear-edge transitional portion, a rear-edge portion containing the rear edge. Dots are formed in the front-edge portion in accordance with a first sub-scanning mode using the fourth sub-group of dot-forming elements without use of any of the first to third sub-groups of dot-forming elements. Then dots are formed in the front-edge transitional portion in accordance with the first sub-scanning mode using the first to fourth sub-groups of dot-forming elements. Dots are formed in the intermediate portion using the first to fourth sub-groups of dot-forming elements in accordance with a second sub-scanning mode. The maximum sub-scan feed amount in the second sub-scanning mode is greater than a maximum sub-scan feed amount in the first sub-scanning mode.
Adopting such an embodiment allows dots to be formed up to the front edge of the print medium without platen soiling. A transfer from the formation of dots in the front-edge portion using the fourth sub-group of dot-forming elements to the formation of dots in the intermediate portion using the first to fourth sub-groups of dot-forming elements can be accomplished in a smooth manner without reversing the feed direction in the course of sub-scanning.
In the formation of dots in the front-edge portion, an arrangement can be adopted in which such dots are formed when the print medium is supported on the platen the front edge of the print medium is above the second slot. Adopting such an embodiment allows dots to be formed without blank spaces along the front edge of the print medium using the forth sub-group of dot-forming elements.
The following printing routine should preferably be adopted after dots have been formed in the intermediate portion. Dots are formed in the rear-edge transitional portion using the second to fourth sub-groups of dot-forming elements without use of the first sub-group of dot-forming elements. The dot forming is performed in accordance with a third sub-scanning mode. The maximum sub-scan feed amount in the third sub-scanning mode is less than the maximum sub-scan feed amount in the second sub-scanning mode. Then dots are formed in the rear-edge portion in accordance with the third sub-scanning mode using the second sub-group of dot-forming elements without use of any of the first, third, and fourth sub-groups of dot-forming elements.
Adopting such an embodiment allows dots to be formed up to the rear edge of the print medium without platen soiling. A transfer from the formation of dots in the intermediate portion using the first to fourth sub-groups of dot-forming elements to the formation of dots in the rear-edge portion using second sub-group of dot-forming elements can be accomplished in a smooth manner without reversing the feed direction in the course of sub-scanning.
During the formation of dots in the rear-edge portion, an arrangement can be adopted in which such dots are formed when the print medium is supported on the platen the rear edge of the print medium is above the first slot. Adopting such an embodiment allows dots to be formed without blank spaces along the rear edge of the print medium using the second sub-group of dot-forming elements.
The present invention can be implemented as the following embodiments.
(1) A dot-recording device, dot-recording control device, or printing device.
(2) A dot-recording method, dot-recording control method, or printing method.
(3) A computer program for operating the device or implementing the method.
(4) A storage medium containing computer programs for operating the device or implementing the method.
(5) A data signal carried by a carrier wave designed to contain a computer program for operating the device or implementing the method.